// Copyright (c) 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef GPU_COMMAND_BUFFER_COMMON_BUFFER_H_
#define GPU_COMMAND_BUFFER_COMMON_BUFFER_H_

#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/memory/scoped_ptr.h"
#include "base/memory/shared_memory.h"
#include "base/trace_event/memory_allocator_dump.h"
#include "gpu/gpu_export.h"

namespace base {
class SharedMemory;
}

namespace gpu {

class GPU_EXPORT BufferBacking {
public:
    virtual ~BufferBacking() { }
    virtual void* GetMemory() const = 0;
    virtual size_t GetSize() const = 0;
};

class GPU_EXPORT SharedMemoryBufferBacking : public BufferBacking {
public:
    SharedMemoryBufferBacking(scoped_ptr<base::SharedMemory> shared_memory,
        size_t size);
    ~SharedMemoryBufferBacking() override;
    void* GetMemory() const override;
    size_t GetSize() const override;
    base::SharedMemory* shared_memory() { return shared_memory_.get(); }

private:
    scoped_ptr<base::SharedMemory> shared_memory_;
    size_t size_;
    DISALLOW_COPY_AND_ASSIGN(SharedMemoryBufferBacking);
};

// Buffer owns a piece of shared-memory of a certain size.
class GPU_EXPORT Buffer : public base::RefCountedThreadSafe<Buffer> {
public:
    explicit Buffer(scoped_ptr<BufferBacking> backing);

    BufferBacking* backing() const { return backing_.get(); }
    void* memory() const { return memory_; }
    size_t size() const { return size_; }

    // Returns NULL if the address overflows the memory.
    void* GetDataAddress(uint32 data_offset, uint32 data_size) const;

private:
    friend class base::RefCountedThreadSafe<Buffer>;
    ~Buffer();

    scoped_ptr<BufferBacking> backing_;
    void* memory_;
    size_t size_;

    DISALLOW_COPY_AND_ASSIGN(Buffer);
};

static inline scoped_ptr<BufferBacking> MakeBackingFromSharedMemory(
    scoped_ptr<base::SharedMemory> shared_memory,
    size_t size)
{
    return scoped_ptr<BufferBacking>(
        new SharedMemoryBufferBacking(shared_memory.Pass(), size));
}

static inline scoped_refptr<Buffer> MakeBufferFromSharedMemory(
    scoped_ptr<base::SharedMemory> shared_memory,
    size_t size)
{
    return new Buffer(MakeBackingFromSharedMemory(shared_memory.Pass(), size));
}

// Generates GUID which can be used to trace buffer using an Id.
GPU_EXPORT base::trace_event::MemoryAllocatorDumpGuid GetBufferGUIDForTracing(
    uint64_t tracing_process_id,
    int32_t buffer_id);

} // namespace gpu

#endif // GPU_COMMAND_BUFFER_COMMON_BUFFER_H_
